You Are a Google AdWords Professional Explaining How Your Client

You are a Google AdWords professional explaining how your client should create a budget for their Google AdWords campaign. The client is confused how Google AdWords determines the lowest possible value for the highest position of the ad. You explain that Google AdWords uses a combination of the Quality Score and the CPC bid. The customer still isn't satisfied and wants a more in-depth explanation. Which of the following is the best description how Google AdWords determines ad ranks in search pages?

A) Google AdWords will divide the Ad Rank of the ad showing above you by your Quality Score, then round off to the nearest cent.
B) Google AdWords will divide the Ad Rank of the ad showing beneath you by your Quality Score, then
C) Google AdWords will divide the Ad Rank of the average bid of all ads competing you're your keywords by your Quality Score, then round off to the nearest cent.
D) Google AdWords considers whoever bids the highest for a keyword and then that person moves to the top of the order.